Hadith 4:383

Narrated Ibn Abi Aufa:

We were afflicted with hunger during the besiege of Khaibar, and when
it was the day of (the battle of) Khaibar, we slaughtered the donkeys
and when the pots got boiling (with their meat). Allah's Apostle made
an announcement that all the pots should be upset and that nobody
should eat anything of the meat of the donkeys. We thought that the
Prophet prohibited that because the Khumus had not been taken out of
the booty (i.e. donkeys); other people said, "He prohibited eating
them for ever." The sub-narrator added, "I asked Said bin Jubair who
said, 'He has made the eating of donkeys' meat illegal for ever.")